LU-1445 lod: Add FLD lookup to LOD

1. Adding FLD in LOD can make it getting the OST index
of the real FID when setting stripEA(l_ost_index) to
the file. Then the client can still use l_ost_index
in stripeEA to locate OST, by which the old client can
still access OST after FID_on_OST is landed.

2. Init sequence client for OSP.

Signed-off-by: Wang Di <di.wang@intel.com>
Change-Id: I559edfd02feb08f32156c7237ec75fe6dde681e3
Reviewed-on: http://review.whamcloud.com/5047
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>